(1) Field of the Invention
The present invention relates to a linear compressor for drawing and compressing refrigerant by a reciprocating motion of a piston driven by a linear motor.
(2) Description of the Prior Art
In refrigeration cycle, it is said that HCFC-based refrigerants such as R22 are stable compounds and decompose the ozone layer. In recent years, HFC-based refrigerants begin to be utilized as alternative refrigerants of HCFCs, but these HFC-based refrigerants have the nature for facilitating the global warming. Therefore, people start employing HC-based refrigerants which do not decompose the ozone layer or largely affect the global warming. However, since this HC-based refrigerant is flammable, it is necessary to prevent explosion or ignition so as to ensure the safety. For this purpose, it is required to reduce the amount of refrigerant to be used. On the other hand, the HC-based refrigerant itself does not have lubricity and is easily melted into lubricant. For these reasons, when the HC-based refrigerant is used, an oil less or oil pure compressor is required, and a linear compressor in which almost no load is applied in a direction perpendicular to an axis of its piston is effective. In this linear compressor, all of its constituent elements arc accommodated in a hermetic vessel, and as a suction tube 85' for introducing the refrigerant into the hermetic vessel, a vessel which is fixed to a rear end plate 81 of a hermetic vessel 80 shown with phantom lines in FIG. 1 is employed.
Although details will be described latter, a piston 20 comprises a rod 22 and a piston head 28 mounted to a front end of the rod 22. Refrigerant introduced from the suction tube 85' into a space 84 of the hermetic vessel 80 passes through the hermetic vessel 80 and mainly through an outer periphery of an outer yoke 52, and is introduced from a suction port 15 of a cylinder 10, and is inhaled and compressed in the piston head 28 and discharged from a discharge mechanism 60.
In this linear compressor, since the piston 20 is provided around its outer periphery with a linear motor 30, the refrigerant introduced into the space 84 from the Suction tube 85' flows forward through a gap between an inner surface of the hermetic vessel 80 and the linear motor 30, and is introduced to the piston head 28 from the suction port 15. By allowing the refrigerant introduced into the hermetic vessel 80 to pass through the linear motor 30 in this manner, the linear motor 30 can be cooled, but the refrigerant is adversely heated. Therefore, there is a problem as compared with refrigerant which is not heated, the compressing efficiency of the refrigerant is lowered correspondingly.
The present invention has been accomplished to solve the above problem, and it is an object of the invention to provide a linear compressor in which a mounting position of a suction tube is contrived to prevent the compressing efficiency from being lowered.
A linear compressor according to a first aspect of the present invention comprises a cylinder supported in a hermetic vessel by a supporting mechanism, a piston which is concentric with the cylinder and is slidably supported along its axial direction, and a linear motor for generating thrust force by forming a magnetic passage by a movable portion secured to the piston and a stationary portion secured to the cylinder, in which refrigerant introduced into the hermetic vessel from a suction tube is inhaled and compressed by reciprocating motion of the piston driven by the linear motor and the compressed refrigerant is discharged out from the hermetic vessel, wherein the suction tube is provided in the vicinity of a suction port leading to a compression chamber formed by the piston and the cylinder.
In the linear compressor according to the first aspect of the present invention, the suction tube for drawing refrigerant is disposed in the vicinity of the suction port leading to the compression chamber. Thus, refrigerant from the suction tube is directly introduced into the compression chamber provided in the vicinity of the suction tube. Therefore, since the refrigerant introduced from the suction tube is not heated by a linear motor, the compressing efficiency is prevented from being lowered.
According to a second aspect, in the linear compressor of the first aspect, the suction tube is opposed to the suction port.
In the linear compressor according to the second aspect of the invention, the suction tube is provided such as to be opposed to the suction port. Therefore, the refrigerant from the suction tube is smoothly and directly introduced to the suction port.
According to a third aspect, in the linear compressor of the first aspect, the suction tube is disposed in a region between a discharge mechanism disposed at one end side of the piston and the linear motor disposed at the other end side of the piston.
In the linear compressor according to the third aspect of the present invention, the suction tube is disposed in the region separated from the linear motor and the discharge mechanism which are heated to high temperature when the compressor is operated. Therefore, the flexibility of positioning of the suction tube is enhanced, the refrigerant is prevented from being heated by the linear motor and the discharge mechanism, and the compressing efficiency is prevented from being lowered.
According to a fourth aspect, in the linear compressor of the first aspect, the piston comprises a piston head and a rod, the linear motor is disposed around an outer periphery of the rod, and the suction port is formed in the cylinder which is adjacent the piston head.
In the linear compressor according to the fourth aspect of the present invention, the suction tube for introducing refrigerant is disposed in the vicinity of the piston head. Thus, the refrigerant from the suction tube is directly introduced to the piston head from the suction port provided in the vicinity of the suction tube. Therefore, the refrigerant introduced from the suction tube is not heated by the linear motor, and the compressing efficiency is prevented from being lowered.
According to a fifth aspect, in the linear compressor of the fourth aspect, the piston head is formed at its one end with the compression chamber and at its other end with a space, the piston head includes a through hole which brings the compression chamber and the space into communication with each other, the piston head also includes a suction valve which opens and closes the through hole, and the suction port is in communication with the space.
In the linear compressor according to the fifth aspect of the present invention, refrigerant introduced to the piston head is introduced into the compression chamber through the space and a through hole, and is inhaled and compressed by operation of a suction valve. Therefore, an influence of heat from high temperature discharged refrigerant is small, and refrigerant can be inhaled and compressed smoothly and efficiently.